1. Field of the Invention
The present invention relates to a control apparatus, a control method, and a computer program of a communication system.
2. Description of the Related Art
In recent years, a technique for realizing transmission of stream data including video signals and audio signals by wireless communication has been developed in a home theater, etc. The home theater includes a plurality of speakers, a display, associated communication terminals, and a control station for controlling the devices and requires a technique capable of playing back high-quality videos and music without interruptions and without fluctuations such as a transmission delay. When transmitting stream data from a video output apparatus to a video playback apparatus, it is difficult for a single communication path to prevent the effect of blocking by an obstacle. Consequently, a technique is proposed to use a plurality of communication paths to redundantly transmit the stream data. In Japanese Patent Laid-Open No. 2009-49932, each communication terminal uses a plurality of time slots to relay and transfer data transmitted from a control station every predetermined period (frame) to improve the reliability of the transmission data.
Furthermore, a technique for dividing the stream data into priority data and non-priority data to transmit the data is proposed. Japanese Patent Laid-Open No. 2002-204273 proposes a technique for transmitting the priority data by a modulation scheme with low modulation rate and transmitting the non-priority data by a modulation scheme with high modulation rate to improve the reliability of the priority data to prevent the user from feeling a degradation in the playback content. Japanese Patent Laid-Open No. 2005-512418 proposes a technique for transmitting the priority data at a high channel encoding rate and transmitting the non-priority data at a low channel encoding rate. In WirelessHD Specification. Version.1.0 Overview (website at wirelesshd.org in the subdirectory WirelessHD_Full_Overview—071009.pdf), proposed is a method of transmitting the priority data and the non-priority data at the same time without selectively using the modulation classes and then retransmitting only the priority data.
Although the reliability of data improves in the redundant transmission scheme in Japanese Patent Laid-Open No. 2009-49932, a large amount of communication band is used. Therefore, it is desired to improve the communication efficiency while maintaining the reliability of redundant transmission in a more suitable communication scheme.
The present invention provides a communication system capable of efficiently using a band to transfer data while keeping the redundancy of communication paths.